DESCRIPTION:(from applicant's abstract): The long-term goal of this project is to understand the cerebellum well enough to build a computer simulation that emulates its function. Several fortuitous features of the cerebellum make it especially amenable to analysis using large-scale, bottom-up computer simulations. The objectives of these simulations is to make our understanding of the cerebellum expressible at the level of information processing: what the cerebellum processes and how. The specific aims build on previous work using the particular advantages of Pavlovian eyelid conditioning to build and test biologically detailed and accurate computer simulations of the cerebellum. The studies of this project will follow a two-pronged approach: capabilities of the simulations will be used as the basis for empirical studies that test underlying mechanisms predicted by the simulations, shortcomings of the simulations will be used as the basis for further development of the simulations. Specific hypotheses will be pursued as to how the addition of specific biological features will alleviate specific shortcomings. In this way the simulations permit a systematic structure-function analysis of cerebellar mechanisms that operate during motor learning. The use of eyelid conditioning as the cerebellar-dependent behavior that the simulations must accomplish provides a rich repertoire of behavioral properties to challenge the simulations and makes the connections the between the simulations and empirical tests of its predictions quite tight. The completion of these studies will provide a relatively clear picture of the basic mechanisms that operate in the cerebellum during learning and adaptation of movements. This should have important future implications for those afflicted with cerebellar damage or degenerative pathologies. In addition, mounting evidence suggests that certain parts of the human cerebellum are involved in non-motor, cognitive process. Since the synaptic organization of these regions and those involved in motor learning do not appear to differ, the cerebellum must contribute the same information processing to both motor and cognitive tasks. The proposed studies therefore represent the ability to study information processing of the cerebellum using quite tractable motor behaviors and then to apply that information to more complex cognitive processes. Thus, these studies will provide a basic understanding of information processing for important aspects of the motor system, and could provide the foundation for a deeper understanding of the neural basis of information processing that is applied to cognitive properties as well.